#!/bin/bash
#pwd
#ls -al

a=5
b=10

if [ $a == $b ]; then
  echo "a==b"
elif [ $a -gt $b ]; then
  echo "a>b"
elif [ $a -lt $b ]; then
  echo "a<b"
else
  echo "未知"
fi

num=$((2 * 3))
num2=$((2 + 3))

if test $((num)) -eq $((num2)); then
  echo "相等"
else
  echo "不相等"
fi

name='lixingwu'
echo $name
echo ${name}

# 输出/etc文件列表
for i in $(ls /etc); do
  echo $i
done

# 只读
readonly username=root
echo username=$username

# 移除变量
unset name
echo name=$name